LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: SeongJae Park <sj@kernel.org>
To: akpm@linux-foundation.org
Cc: john.stultz@linaro.org, tglx@linutronix.de, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, SeongJae Park <sj@kernel.org>
Subject: [PATCH v2 1/2] timers: Implement usleep_idle_range()
Date: Thu, 25 Nov 2021 16:08:29 +0000	[thread overview]
Message-ID: <20211125160830.30153-2-sj@kernel.org> (raw)
In-Reply-To: <20211125160830.30153-1-sj@kernel.org>

Some kernel threads such as DAMON could need to repeatedly sleep in
micro seconds level.  Because usleep_range() sleeps in uninterruptible
state, however, such threads would make /proc/loadavg reports fake load.

To help such cases, this commit implements a variant of usleep_range()
called usleep_idle_range().  It is same to usleep_range() but sets the
state of the current task as TASK_IDLE while sleeping.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/delay.h | 14 +++++++++++++-
 kernel/time/timer.c   | 16 +++++++++-------
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/include/linux/delay.h b/include/linux/delay.h
index 8eacf67eb212..039e7e0c7378 100644
--- a/include/linux/delay.h
+++ b/include/linux/delay.h
@@ -20,6 +20,7 @@
  */
 
 #include <linux/math.h>
+#include <linux/sched.h>
 
 extern unsigned long loops_per_jiffy;
 
@@ -58,7 +59,18 @@ void calibrate_delay(void);
 void __attribute__((weak)) calibration_delay_done(void);
 void msleep(unsigned int msecs);
 unsigned long msleep_interruptible(unsigned int msecs);
-void usleep_range(unsigned long min, unsigned long max);
+void usleep_range_state(unsigned long min, unsigned long max,
+			unsigned int state);
+
+static inline void usleep_range(unsigned long min, unsigned long max)
+{
+	usleep_range_state(min, max, TASK_UNINTERRUPTIBLE);
+}
+
+static inline void usleep_idle_range(unsigned long min, unsigned long max)
+{
+	usleep_range_state(min, max, TASK_IDLE);
+}
 
 static inline void ssleep(unsigned int seconds)
 {
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index e3d2c23c413d..85f1021ad459 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -2054,26 +2054,28 @@ unsigned long msleep_interruptible(unsigned int msecs)
 EXPORT_SYMBOL(msleep_interruptible);
 
 /**
- * usleep_range - Sleep for an approximate time
- * @min: Minimum time in usecs to sleep
- * @max: Maximum time in usecs to sleep
+ * usleep_range_state - Sleep for an approximate time in a given state
+ * @min:	Minimum time in usecs to sleep
+ * @max:	Maximum time in usecs to sleep
+ * @state:	State of the current task that will be while sleeping
  *
  * In non-atomic context where the exact wakeup time is flexible, use
- * usleep_range() instead of udelay().  The sleep improves responsiveness
+ * usleep_range_state() instead of udelay().  The sleep improves responsiveness
  * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces
  * power usage by allowing hrtimers to take advantage of an already-
  * scheduled interrupt instead of scheduling a new one just for this sleep.
  */
-void __sched usleep_range(unsigned long min, unsigned long max)
+void __sched usleep_range_state(unsigned long min, unsigned long max,
+				unsigned int state)
 {
 	ktime_t exp = ktime_add_us(ktime_get(), min);
 	u64 delta = (u64)(max - min) * NSEC_PER_USEC;
 
 	for (;;) {
-		__set_current_state(TASK_UNINTERRUPTIBLE);
+		__set_current_state(state);
 		/* Do not return before the requested sleep time has elapsed */
 		if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS))
 			break;
 	}
 }
-EXPORT_SYMBOL(usleep_range);
+EXPORT_SYMBOL(usleep_range_state);
-- 
2.17.1


  reply	other threads:[~2021-11-25 16:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-25 16:08 [PATCH v2 0/2] mm/damon: Fix fake /proc/loadavg reports SeongJae Park
2021-11-25 16:08 ` SeongJae Park [this message]
2021-11-25 16:08 ` [PATCH v2 2/2] mm/damon/core: Fix fake load reports due to uninterruptible sleeps SeongJae Park
2021-11-26 14:37 ` [PATCH v2 0/2] mm/damon: Fix fake /proc/loadavg reports Oleksandr Natalenko
2021-11-26 14:41   ` SeongJae Park

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20211125160830.30153-2-sj@kernel.org \
    --to=sj@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=john.stultz@linaro.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=tglx@linutronix.de \
    --subject='Re: [PATCH v2 1/2] timers: Implement usleep_idle_range()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).